I plan to move in San Francisco in Feb-March 2011. I am 58 y.o. female; I would like to rent an affordable place preferably in smaller buildings, with

I would like it be one bedroom, hardwood floors, safe neighborhood. I drive, so the place could be within 15-20 min driving from the heart of San Fr. I heard about communities 55 . Where do I find them?

Most of San Francisco's neighborhood fit a bit of your description, however, "communities 55" is something that might not be as readily available in the fashion you're describing. I know of a condominium complex in the heart of the Mission that is specifically for older folks, but there are certain conditions (I am not privy to all these as these are rentals and I personally don't handle that side of the formula), but, the area where these condos are leave much to be desired in the way of safety -- they are near the BART station, (rapid transit), and there are far too many people in and around the area to be safe. On the other hand, if you find things online, as responders have said, craigslist, you may narrow your search by checking online first then checking the areas once you're here. Good luck.